Recently, various high-speed digital wireless systems such as a wireless LAN, Bluetooth, Terrestrial Digital Television have been put to practical use. Most of these wireless systems are realized by a circuit formed on a semiconductor chip, that is, an on-chip inductor.
Various types of inductors have ever been disclosed as an on-chip inductor. Inductors disclosed in Patent Literature 1 (Japanese Patent Application Publication No. 07-142258), Patent Literature 2 (Japanese Patent Application Publication No. 08-017656) and Patent Literature 3 (Japanese Patent Application Publication No. 2006-245455) are inductors in which go-around wiring is formed on a semiconductor substrate in a planar manner via an insulating layer.
An inductor disclosed in Patent Literature 4 (Japanese Patent Application Publication No. 2004-140165) is an inductor in which go-around wiring is formed in a wiring layer on a substrate in a planar manner.
An inductor disclosed in Patent Literature 5 (Japanese Patent Application Publication No. 2001-267512) is an inductor in which spiral patterns each having the same shape are formed on two upper layers thereof in a three-layer wiring structure formed on a Si substrate and they are connected in parallel.